1. Field of the Invention
The present invention relates to an electrically programmable and electrically erasable nonvolatile semiconductor memory.
2. Description of the Related Art
Conventionally, EEPROM, by which data is electrically rewritable, is known as one of semiconductor memories. Above all, a NAND type EEPROM (a NAND type flash memory device), which has NAND type cells configured of a plurality of memory cells and which is a unit storing 1 bit being connecting in series, has received much attention. The NAND type flash memory device, for instance, is utilized as a memory card for storing image data of digital still cameras.
In recent years, progress has been made with larger capacity NAND type flash memory devices, and the programming unit (page capacity) and erase unit (block capacity) has also become larger, for example, Published and Unexamined Japanese Patent Application (kokai) No. 2002-133877.